This invention relates to a radial vane type of pump assembly having flow rate varying facilities associated therewith.
Adjustable radial vane pumps having an angularly adjustable annular control ring in the pump housing, is already well known as described for example in SAE Publication No. 790725 of June 1979. Page 7 and FIG. 10 in said publication describes such a pump wherein the annular control ring is supported in the pump housing for pivotal displacement by means of a pivot pin fixed to the housing. On a radial side opposite the pivot pin, the housing is provided with a seal mounted on the annular control ring. Two pressure chambers are thereby formed in the housing, one of which is connected to the pump outlet while the other is connected to the pump inlet. The outlet connected pressure chamber is provided with a spring urging displacement of the annular control ring against the bias of the outlet pressure. The differential outlet pressure that is developed effects displacement of the annular ring member in one direction to reduce the radial stroke of the pump vanes between which fluid displacing chambers are formed to thus regulate the pump flow rate. The housing of the foregoing pump assembly has a so-called "sandwich" type of configuration formed by an intermediate annular housing section and the end covers. In order to obtain satisfactory sealing in all adjusted position of the annular control ring, associated arcuate sealing surfaces in the housing are formed with reference to the pivot point about which the annular control ring is angularly displaced. The manufacture of the housing assembly pursuant to the foregoing prior art arrangement is extremely costly.
It is therefore an important object of the present invention to provide a less costly radial vane type pump having an angularly adjustable flow rate, regulating annular control ring with an acceptable sealing arrangement for a relatively large and variable radial sealing gap.